“…LPHA was prepared from a single batch of PHA-P (Difco Laboratories, Detroit, MI) according to a modification of the column chromatography method of Webber et al 181, as previously described [9]. This homogeneous mitogenic glycoprotein was utilized for both metabolic and receptor studies at concentrations appropriate for the purpose intended and based upon known receptor occupancy and metabolic response profiles previously reported [9,10]. For receptor studies, LPHA was iodinated (reduc-ta~~t-free'*~I, specific activity 17 Ci/mM, ICN, Life Sciences Group, Irvine, CA) by the chloramine-T method of Hunter [ll] and adjusted to a final specific activity of 150,000 CPM/pg LPHA-protein in 0.5% albumin (bovine serum albumin, Grand Island Biological Co., Grand Island, NY).…”